the 12 Core Mac

[D Tibbets]

Don't forget the harsh environment of space. I think they do use off the shelf portable computers on the international space station for various reasons. But is the flight critical computing systems space hardened? Low Earth Orbit is fairly benign for space enviorments. Once you enter the radiation belts and travel past them you are exposed to significant radiation- mostly charged particles from the Sun. Do geostationary satellites use hardened computers? Intel at one time made space hardened processors. I have no idea of current standards.

ps: Some introductory considerations here:

http://en.wikipedia.org/wiki/Radiation_hardening

Dan Tibbets

[palladin9479]

My understanding is that you don't need the CPU itself to be hardened but rather the container it's in. Rad hardening a single chip is useless cause there is a higher probability it'll strike one of the PCB traces and cause a jump in voltage that could interfere with the bus's. You need to harden everything being used, especially if high speed data bus's are present as they extremely sensitive to timing. A pretty good faraday cage design that enclosed all the sensitive computational equipment would have to be used.

[ladajo]

The problem is also similar in ways to EMP hardening.

[Skipjack]

My software loves many core CPUs
On the rad hardening. I think a lot of the rad hardening is just redundancy. IIRC SpaceX has triple redundant computers that keep each other in check.

[hanelyp]

palladin, it isn't just probability of a circuit element intercepting a particle of radiation, but the likely results. A circuit board trace is massive enough that a cosmic ray is minor noise. A transistor in a CPU, on the other hand, is very tiny and sensitive to variations in conductivity of whatever material is hit. A transistor in the off state could be momentarily turned on by the ion trail left.

[palladin9479]

palladin, it isn't just probability of a circuit element intercepting a particle of radiation, but the likely results. A circuit board trace is massive enough that a cosmic ray is minor noise. A transistor in a CPU, on the other hand, is very tiny and sensitive to variations in conductivity of whatever material is hit. A transistor in the off state could be momentarily turned on by the ion trail left.

Already said this

You need to harden everything being used, especially if high speed data bus's are present as they extremely sensitive to timing.

It's no longer "minor noise" if it interferes with the timing signal. Modern bus's transfer data on both the rising and falling edge of the clock signal at high frequency. If you screw with the timing or alter the voltage slightly at the wrong moment it will cause a bit to flip during transit and your computational results become invalid, without you even knowing about it. This is why modern high performance CPU's are coming equipped with a form of ECC to check the validity of the data coming across the bus and the results coming out of the CPU.